In a mobile network, a mobile node may be constantly moving from one cell served by one access point to a second cell served by a different access point. In order to enable the mobile node to constantly interact with other mobile nodes, it is essential to maintain communication between the mobile node and at least one access point in the mobile network. The process of handing over a communication link from one access point to another is known as handoff.
The most common criteria for determining the need for a handoff are Received Signal Strength (RSS) and/or Signal to Noise Ratio (SNR). When a mobile node shifts from one cell to another, it registers a drop in RSS and/or SNR. The mobile node then scans for a new access point, which can provide service to the mobile node in the new cell. Upon finding the new access point, the mobile node interacts with it and uses its services.
However, the method of handoff, as described, suffers from a number of limitations. First, the method may not always be able to achieve a smooth handoff. For example, if the mobile node starts scanning early (while it is still in contact with an old access point), it may discover a new access point. The mobile node may then loose connectivity to the new access point, while still being able to talk to the old access point. The mobile node then has to scan again, resulting in wastage of battery and network resources. If the mobile node starts scanning late, it may not be able to discover a new access point even after loosing connectivity with the old access point. This results in inefficiencies in the handoff process.
Second, there are certain areas in a mobile network where RSS and SNR decrease rapidly with very short movement. In other areas, they may decrease and increase alternately with straight-line movement. In such areas, the use of RSS and SNR values for deciding the need of handoff can make the process inefficient.
Accordingly, there is a need for an improved handoff method and system.